1. Field of the Invention
The present invention relates to a lens moving device which is provided in a digital camera, for example, to move a photographing lens along the optical axis thereof.
2. Description of the Related Art
Conventionally, there is known a lens moving device, provided in a digital camera, in which a nut is threaded on a feed screw directly connected to an output shaft of a motor and this nut is connected to a lens frame to which a photographing lens is attached, so that the photographing lens is moved to a target stopping-position in accordance with the result of photometry. In this device, the nut and the lens frame are connected to each other by inserting an arm member provided to the nut into an arm insertion opening formed in the lens frame. Accordingly, the driving force of the motor is transmitted to the lens frame and the photographing lens via the arm member.
If the spring force of the arm member is relatively small, the arm member will bend because of the load of the lens frame etc., to hence the lens frame and the photographing lens will not follow the operation of the motor and a delay will occur. Namely, the driving force of the motor required to move the lens to the target stopping-position, is not exactly transmitted to the photographing lens. Therefore, for reducing the bend caused by lens movement, an arm member having a large spring force is suitable. However, when the arm member is inserted into the arm insertion opening during the assembling process of the device, the arm member should be bent, and if the spring force of the arm member is too large, the assembly would be difficult.
Therefore, an object of the present invention is to provide a lens moving device in which the spring force is large enough to provide precise control of the position of the photographing lens, and for which the assembling process is easy.
According to the present invention, there is provided a lens moving device comprising a support mechanism and a drive mechanism. The support mechanism supports a lens in such a manner that the lens moves along the optical axis thereof. The support mechanism is provided with a single arm-receiving opening. The drive mechanism moves the lens along the optical axis. The drive mechanism is provided with a first arm having a first spring force, and a second arm having a second spring force less than the first spring force. The first and second arms are arranged in order along the line, in which the lens is moved, and they are inserted in the arm-receiving opening so that the drive mechanism is connected to the support mechanism.
Further, according to the present invention, there is provided a device for moving a lens along the optical axis thereof, the device comprising a lens frame to which the lens is attached and a drive mechanism. The lens frame is provided with an arm-receiving opening. The drive mechanism moves the lens frame along the optical axis. The drive mechanism is provided with first and second arms. The first arm has a spring force, which is greater than that of the second arm. The first and second arms are extended perpendicularly to the optical axis, and inserted in the arm-receiving opening so that the drive mechanism is connected to the support mechanism.